1. Field of the Invention
The present invention relates to sheet material feeding devices that feed sheet materials, as recording media, to recording apparatuses such as facsimiles, copiers, and printers.
2. Description of the Related Art
There are many known commercial recording apparatuses each including a plurality of sheet material stacking units that are arranged one above the other. An example of such recording apparatuses is shown in FIG. 10.
FIG. 10 is a schematic cross-sectional view of a known recording apparatus that includes a plurality of sheet material stacking units. The recording apparatus in FIG. 10 includes a first sheet material stacking unit 45 and a second sheet material stacking unit 46 that are arranged one above the other. The recording apparatus further includes, between the first sheet material stacking unit 45 and the second sheet material stacking unit 46, a first feeding mechanism 44 having a feeding roller 42 that feeds sheet material P4 from the first sheet material stacking unit 45. Above the second sheet material stacking unit 46, the recording apparatus includes a second feeding mechanism 43 having a feeding roller 41 that feeds sheet material P3 from the second sheet material stacking unit 46. In short, the first sheet material stacking unit 45, the first feeding mechanism 44, the second sheet material stacking unit 46, and the second feeding mechanism 43 are arranged in that order from the bottom to the top.
FIGS. 11A and 11B show another known recording apparatus in which a single feeding mechanism accommodates a plurality of sheet material stacking units.
In the recording apparatus shown in FIGS. 11A and 11B, sheet material is fed from each of the plurality of sheet material stacking units by the use of the single feeding mechanism. Specifically, the sheet material is fed in the following manner.
To feed sheet material P6 stacked in a first sheet material stacking unit 53 to a recording unit, referring to FIG. 11B, a second sheet material stacking unit 52 is retracted to a −Y side with respect to a feeding mechanism 51 in a sheet material conveying direction and is secured there. In this state, a feeding roller 51a of the feeding mechanism 51 presses the sheet material P6 stacked in the first sheet material stacking unit 53, and the sheet material P6 is fed toward a pair of rollers 54 disposed in a sheet material conveying path. The sheet material P6 that has reached the pair of rollers 54 is further delivered through pairs of rollers 55 and 56 and to the recording unit.
To feed sheet material P5 stacked in a second sheet material stacking unit 52 to the recording unit, referring to FIG. 11A, the second sheet material stacking unit 52 is moved to a +Y side in the sheet material conveying direction and is secured below the feeding mechanism 51. In this state, the feeding roller 51a of the feeding mechanism 51 presses the sheet material P5 stacked in the second sheet material stacking unit 52, and the sheet material P5 is fed toward the pair of rollers 54 as in the case of feeding the sheet material P6 from the first sheet material stacking unit 53. The sheet material P5 that has reached the pair of rollers 54 is further delivered through the pairs of rollers 55 and 56 and to the recording unit, as in the case of the sheet material P6.
In the recording apparatus having such a configuration, it is general that the second sheet material stacking unit 52 is provided for sheet materials of relatively small sizes, such as the postcard size and the L size. In contrast, it is general that the first sheet material stacking unit 53 is provided for sheet materials of relatively large sizes, ranging from A5 to A4.
The configuration shown in FIG. 10 has a problem in that the necessity of disposing the feeding mechanism 44 between the sheet material stacking unit 45, the lower one, and the sheet material stacking unit 46, the upper one, increases the height of the sheet material feeding device and, consequently, the height of the recording apparatus.
In the configuration shown in FIGS. 11A and 11B, in which the single feeding mechanism 51 is shared between the sheet material stacking units 52 and 53, the heights of the sheet material feeding device and the recording apparatus can be made smaller than in the configuration shown in FIG. 10. However, the configuration shown in FIGS. 11A and 11B has another problem. In both configurations shown in FIG. 10 and FIGS. 11A and 11B, an angle of a certain magnitude needs to be formed between the feeding roller and the sheet material because the sheet material can only be fed by a force (biting force) with which the feeding roller presses the sheet material.
From this viewpoint, the configuration shown in FIGS. 11A and 11B forms angles θ1 and θ2 between the feeding mechanism 51 and the sheet materials P5 and P6 by having the feeding mechanism 51 angled with respect to the sheet material stacking units 52 and 53. However, since the feeding mechanism 51 is shared between the upper and lower sheet material stacking units 52 and 53, the angle θ1 formed between the feeding mechanism 51 and the sheet material P5 stacked in the sheet material stacking unit 52 positioned nearer to the feeding mechanism 51 is smaller than the angle θ2. As a result, the force (biting force) with which the feeding roller 51a presses the sheet material P5 is reduced and, therefore, feeding of the sheet material may become unstable.
From the viewpoint of realizing stable feeding of the sheet material, the angles θ1 and θ2 are both desired to be within the range of about 5 to 20 degrees. However, if the feeding mechanism 51 and the sheet material stacking units 52 and 53 are arranged such that the angles θ1 and θ2 both fall within the foregoing range, the number of stackable sheets of the sheet materials P5 and P6 and the height of the sheet material stacking units directly affect the height of the sheet material feeding device and, consequently, the height of the recording apparatus.